


The Prince's Promise

by orphan_account



Category: Shadowhunters (TV)
Genre: M/M, Malec, Post 3a, Post 3x10, Some Fluff, magnus and asmodeus flashback, magnus banishes asmodeus, of course though, some sad
Language: English
Status: Completed
Published: 2019-02-10
Updated: 2019-02-10
Packaged: 2019-10-25 10:17:03
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,688
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17723288
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: Magnus banishes Asmodeus, and continues to bear the consequences centuries later.





	The Prince's Promise

**Author's Note:**

> I don't know what this is.

                Magnus had his hands held up in front of his face, his fingers emitting a soft blue light, his heavy pants and the ice-cold wind that blew past the only sounds for miles. The row of buildings on either side of him had been vacated in a haste, the snow was beginning to fall again, thickening the white terrain already surrounding them.

                “Do you see now?” Asmodeus taunted, and Magnus shut his eyes. “With all your power, your attempts to harm me are useless.”

                Magnus ducked his head, though he did not dare lower his hands.

                “I will forgive you, my son,” Asmodeus said, and had Magnus not been so accustomed to hearing his father persuade others to their deaths, he might’ve believed he was being sincere. “This is not your fault. It is the human blood that runs in you, it begs too much of you. _That_ is why you feel this senseless sympathy for other creatures.”

                “Stop—”

                “ _That_ is why you ache. Let me strip you of that weakness!”

                “NO!” Magnus felt tears fall down the bridge of his nose. “I don’t want to be a demon—”

                “A demon is what you are!” Asmodeus said. He seemed to be getting angry now. “You are a prince of Edom, you should be proud!”

                “No,” Magnus clenched his jaw. “I don’t… I don’t want to be a prince—I DON’T WANT TO BE YOUR SON!”

                Asmodeus went silent, and Magnus dared look up to see his father shaking where he stood. He opened his mouth slowly, as if even he was afraid of what he would do.

                “Be very careful… what you say to me, _boy_ ,” he threatened. “No one— _no one_ will love you as I do.”

For a moment, time seemed to slow down, and the white clouds, the falling snow, the empty buildings, the abandoned streets—they bore him a message: _it was time_.

“I know,” he finally said to his father, “and I will have to live with that.”

                Asmodeus took a step forward, and winced, his jaw clenched. He crouched over, clutching his thigh. Magnus’s eyes widened. Asmodeus’s leg was injured, and it had only drained most of Magnus’s magic to do it. He took deep breaths as he urged the magic in his hands to strengthen, and the blue flames grew brighter.

                If he was going to do this, he had to do it now.

                “ENOUGH!” Asmodeus snapped. Strands of his hair fell on his face, his cat eyes darkened, and with his shouts, the wind whipped around, throwing snow and nearly pushing Magnus off his feet. “Do you honestly believe you can kill me? _ME?!_ ”

                Magnus shook his head. The tears would not stop. He feared they never would again. “No… I don’t want to kill you. You’re my father. I wish we could stay together, and I could believe that you were all I needed again, and we could be—WE COULD BE BETTER THAN THIS!”

                He brought his hands together, “But I can’t let anyone else get hurt… and if I have to suffer alone for the rest of my existence to pay for what I’ve done, then so be it.”

                Asmodeus’s brows furrowed. “What do you…”

                His words trailed off as the ground shook beneath him, and all of a sudden, a large star with a circle drawn around the ends burned into the snow under Asmodeus’s feet, trapping him inside.

                His eyes widened. “The Seal of Edom.”

                “I can’t kill you,” Magnus said, his hands shaking. “I won’t… but I can keep you in your kingdom, and make sure you never leave.”

                “You dare banish me?” Asmodeus whispered. “THE ONE WHO SAVED YOU?!”

                Magnus shut his eyes tight, trying hard not to think of losing his father, not to think of the years ahead that he would have alone, not to think of the tortured and dead he would have to atone for, and instead focused on his objective. The kingdom of Edom.

                He could feel the power of Edom rising, almost taking in whatever it could within the seal, and it looked like Asmodeus could sense it too because he started to panic.

                “You will not be welcomed back into my kingdom, Magnus Bane, OR MY HEART!” The snow melted as flames began to rise from the seal, and Asmodeus stumbled because of his bad leg. “I will watch you for eternity – whatever you give, I will take from you! You will lose your heart and soul, and you will stand here before me, once again, ALONE!”

                The weight on his bones was so strong that Magnus felt himself about to faint, but he dug his heel into the ground and forced himself to keep fighting through the pain.

                He lowered his arms, his palms facing down.

                “Magnus,” Asmodeus finally said, his eyes staring into Magnus’s, “if you do this, you _will_ lose everything.”

                Magnus searched his father’s face for any indication of remorse, any sorrow at what he’d done, _any_ excuse for Magnus to stop this. But he showed none, and Magnus knew in that moment that everything had already been lost.

                With a shout, Magnus forced every bit of power in his body into his final move, bringing his arms up in a strong thrust. For a split second, he’d hoped it would not work, but the flames rose higher than the buildings, the wind blew wildly, and Asmodeus screamed for Magnus before the flames suddenly died, and he was gone.

                The snow around the flames had remained cool and untouched, the seal was gone, replaced by a giant burning circle in the ground, and except for Magnus’s breathing, the world had turned to silence. Any strength Magnus was using to keep himself up was gone now, and he collapsed onto the ground, his face half-buried in the snow.

                His face was bruised, his body beaten and cut into, but nothing hurt as much as his heart. Even in this open air, he felt suffocated. The man that had guided him for years, who’d held his hand and carried him on his shoulder, who’d pulled him from the fires and showed him all the horrors of his kind, was now gone. And Magnus was alone.

                Magnus woke in a cold sweat, bolting upright in his bed, and he was instantly aware of three things; the sleeping draught he’d made had done nothing to soothe the nightmares that had been haunting him for the past week; the magic he’d felt coursing through him so vividly only a moment ago was gone now, his heart racing as if it knew better than Magnus that without it, he was just as lost and defenseless as he had been out in that snow; and there was an arm around his waist, another one on his naked back. Alec had instantly woken up with Magnus, sitting up with his arms around his boyfriend, rubbing soothing circles into his skin.

                Alec’s voice was groggy as he whispered calming words into Magnus’s ear, his eyes half-lidded as if he was trying very hard to properly wake himself up.

                “I’m right here,” he promised. “I’m right here.”

                “I’m sorry,” Magnus breathed. He placed a hand on his heart, trying to take deep breaths, but every time he closed his eyes, he saw his father’s face.

                “Don’t be sorry,” Alec shushed him, repeating the words he’d said every night since Magnus had returned from Edom, his magic gone, a piece of his core forever missing. Sometimes Magnus just needed the confirmation that it was okay to be broken after what he’d lost, but it didn’t work tonight. He still felt cold, his fingers numb, his mind flashing with images of he and his father all those years ago, standing opposite one another.

                Magnus had been sure he was going to die that day, and for the longest time afterwards, he’d wished he had. Now, it was back. That cold, creeping feeling in his bones, telling him he was just as helpless, just as useless, just as lost as he had been after he’d sent his father—the only family he’d ever known and loved after his mother—away, lying in the snow, very close to death.

                He shut his eyes, allowing Asmodeus’s face to taunt him. Fear was better than nothing; a welcome distraction from the fact that the tingling in his muscles, the electricity that constantly ran through his spine, the heat behind his eyes that allowed for the reveal of his true, inhuman, slit-pupils—all of it was gone.

                Then, Alec placed a kiss on his forehead, slow and soothing, then to his cheek, and Magnus woke from his haze with a small gasp, as if being narrowly pulled out a black hole that had nearly engulfed him.

                He sighed, bringing an arm around Alec’s naked waist, burying his face in his shoulder. _I was almost taken in_ , Magnus thought with a numb sort of panic. _I have to be more careful._

                He couldn’t let his thoughts wander like that. It was a dangerous place to go, the memories of his father. A place that had all but consumed Magnus for the entirety of his long lifetime.

_Of course_ , Magnus couldn’t help but think, _that lifetime will soon come to an end._

                Magnus pursed his lips, placing a soft kiss to Alec’s collarbone in hopes of bringing himself back to the present. He was here with Alec. What more could he have wanted?

                “Was it your father again?” Alec asked, his voice hoarse from a dry throat.

                Magnus held on tighter to Alec, and said nothing. He shook his head slightly, hoping it would be enough, and in response, Alec hugged him closer to his chest, bringing them both to lie back down on the bed. Magnus was faintly aware of Alec’s hands, touching him wherever he could reach, and he knew that Alec wouldn’t fall asleep until he did.

                So, Magnus did the only thing he could; he faked it. In half an hour, after his eyes had shut, his breathing slow and deep, Magnus felt Alec finally sleeping underneath him. He tilted his head up, looking at the Shadowhunter’s angelic face—Nephilim or not, he was certain only Alec Lightwood could look that beautiful and majestic—and for a moment, all Magnus could think of was Alec. His Alec, safe, protected, here with him.

                Magnus’s hand involuntarily tightened on his waist, and he was instantly reminded of the lack of spark in his fingertips, the blue flame that was now nothing but a memory, though it felt as if it would return any day to him. Because Magnus without his magic was _wrong_ , unnatural. He wasn’t Magnus Bane without his powers.

                _And if I’m not Magnus Bane…_

                Magnus silently and carefully removed himself from Alec’s hold, placing a soft kiss to the back of his boyfriend’s hand before gently setting it on the bed.

                He slipped on his black, silk robe, his eyes lingering on the rings on his bedside table, the ones he wore more than most, each engraved with his initials; _M_ and _B_. Wearing them now made him feel like a liar.

                With a quiet sigh, he turned away, left the bedroom, and made his way into the apothecary. Aside from a few ingredients that rested on the table from his recent attempt at a sleeping potion, and a small cauldron that still smelled of matchsticks and roses, the room had been left untouched since the night he created the pentagram that had taken him to Edom.

                He tried not to think of that day, the decision he’d made and everything that had been involved, and took his seat in the large armchair behind his desk. His eyes caught the small wooden box tucked away in the corner of one of his shelves, and he looked away. He didn’t think he could bear going through his mementos now, thinking of the lost loves he’d suffered because of his immortality. It seemed unfair. Had the people in that box known that one day, in the distant future, the warlock they’d fallen in love with would become a captive of time, just like everyone else, would things have been different?

                Magnus closed his eyes, and groaned into his hands. _Don’t open that door_ , he thought. _Don’t torture yourself. It’s in the past; no matter what the circumstances now, they were part of your past. Let them rest._

                He was tired— _exhausted_ , yet he knew that sleep would be impossible now. He looked around his apothecary; the parchment rolled and tucked into corners and on the floor against the shelves; the exotic potted plants that lined the wall on one end, and scattered around the room, here and there, amongst the spell books and small glass bottles of black gravel; the old language and fairytale books that Magnus had collected over the years from different countries, packed and stuffed unceremoniously on the shelves beside the many, many, _many_ jars filled with rare and unusual ingredients; from dragon scales to griffin feathers.

                _I should find someone to take those before they expire_ , Magnus thought fleetingly. It would’ve been such a waste otherwise.

And his shoulders fell, his back slumped slightly against his chair. What a sad thought, to think of the things in this room he’d have to get rid of or give away. Without his magic, there was no point to it.

                Maybe Magnus was selfish. Maybe it was wrong to want more, with his boyfriend sleeping in the next room. Then his eyes fell on his mother’s keris, the one he kept displayed every day because it reminded him of his mother. As much as she hated him for what he was, it was the only memento he had of hers. It had never been the keris that had killed his mother after all, it had been him. Magnus was the murderer, the deadliest weapon, and though he knew he should be glad that the part of him that had been responsible for his mother’s murder, that the cat eyes she had been so afraid of were now gone forever—that it was all gone, he only felt his despair, his sorrow, his anger, _grow_.

                He’d lost his powers now, when it was too late. His mother was already gone, his loves already passed, the lifetimes already endured. And now, he was left on the other side of it all, safe in his home with the man he loved, but what pain he’d destroyed in his heart was already reforming at the loss of his core-self. His magic was gone. He was no longer a warlock.

                “Magnus?” there was a soft knock on the door, the voice that called softer still.

                Alec stepped in, dressed and worried, just as Magnus stood, straightening his features to a calm weariness. He approached him almost cautiously, as if afraid that Magnus would push him away if he came too close.

                Magnus took pity, and closed the distance between them. His hands went to Alec’s arms as Alec’s automatically went to his waist, pulling their bodies together. He breathed a sigh of relief, his fingers stretched out over the expanse of Magnus’s hips. “You should’ve woken me up.”

                “I wanted to,” Magnus confessed, “but I couldn’t bring myself to do it.”

                Alec looked around the apothecary, his brows furrowed as if he could sense the misery in Magnus’s voice, and he blamed the parchment and books for it.

                “Magnus, this is me,” Alec said, all trace of fatigue gone from his voice. He looked fully awake, alert, and there was a faint plea in his tone. “Whatever you’ve been thinking, I can take it. You can tell me.”

                And somehow, Magnus heard the silent words; _I know you’re angry at me. Yell at me, curse me, do whatever you want; I deserve it._

                Magnus shook his head, his brows furrowed. He leaned forward and pressed a gentle kiss against Alec’s lips, not missing the way Alec’s fingers tightened on him, keeping him in place.

                Magnus had only meant it to be a second’s kiss, but Alec wouldn’t let him move, his lips taking Magnus’s again and again, deepening the kiss every time.

                Magnus’s eyes closed as he leaned into Alec, the Shadowhunter’s hands coming around back, keeping them both steady. Magnus sighed contentedly, feeling—for the first time in days—like he could breathe.

                Then he saw his father, smiling at him from behind bars of fire. His cat eyes glimmering in the darkness, and behind him, a red sky too familiar and horrible. Magnus jerked back, his eyes wide. His hands had, of their own accord, pulled away from Alec, keeping him at an arm’s length.

                “Magnus,” Alec, looking a little dazed from the kiss, and, at the same time, alarmed, said, “w-what’s wrong? What—what happened?”

                “Nothing,” but Magnus had already turned away, rubbing his face. He was exhausted. That was all that was; a flashback of his nightmare. He was fine. And yet…

                He looked over his shoulder at Alec who now looked properly concerned, and he thought of his father.

_“I will watch you for eternity – whatever you give, I will take from you! You will lose your heart and soul, and you will stand here before me, once again, ALONE!”_

                Asmodeus’s words rang in his ears. _It was centuries ago_ , Magnus thought. Alec was safe, no one would touch him. Magnus would make sure of it.

And there it was again; that reminder that no magic coursed through Magnus’s veins, his demonic power promising no threat of vengeance to anyone who dared hurt the ones he loved. He could do nothing.

                He felt Alec’s hand on his elbow, and was vaguely aware of the Shadowhunter speaking to him, but he couldn’t hear a word. All he could think of was Asmodeus finding Alec, hurting Alec, taking Alec away, and Magnus being incapable of saving him. Incapable of saving anyone.

                Magnus flinched from his touch, and barely caught a look of the hurt that flashed his face—the readiness to take whatever Magnus threw at him with a set jaw, clenched fists, and shining eyes—before the ex-warlock turned away, unable to look at him any longer.

                “Return to the Institute,” he said quietly. “Don’t come back tomorrow.”

                “W-What?”

                Magnus could hear the pain in his voice, but as much as he longed to wrap his arms around the younger man, to tell him that he loved him and that he would give his life to keep him safe, he couldn’t. He couldn’t do anything but talk to Catarina, tell her what had happened. She—aside from Ragnor, after all—was the only one who knew the truth about Magnus and his past. She would know how to help him protect Alec. The right spell, the right incantation, the right sigils… whatever it took. He would keep Alec safe.

                “Go,” Magnus said, louder this time.

                “Magnus,” Alec tried again, and Magnus felt him stand directly behind him, his fingers barely brushing Magnus’s waist. “Look, I… y-you’re angry, I know, but please, don’t make me leave you—”

                “Just _go_ , Alec!” he snapped, then saw Alec fidget with his hands nervously, his eyes wide and afraid, as if he had unintentionally committed a horrible crime against Magnus and realized he would never be forgiven for it.

                Magnus pushed his fear aside, and sighed, taking Alec’s face in his hands. Alec immediately held his wrists, his grip tight, as if worried that Magnus would move away again, tell him to leave.

                “I’m sorry,” Magnus said. “I love you. I just… need you to go.”

                “Magnus, come on,” Alec said desperately. “I know something’s happening, why don’t you tell me what it is? I could protect you.”

                “No,” Magnus shook his head. “No. Please, Alexander, I need you to trust me.”

                “Magnus—”

                “ _Trust me_ ,” Magnus said, and stepped out of Alec’s hold. At least, he tried, but Alec’s vice-like grip wasn’t allowing it. He sighed. “Alexander, let me go.”

                But Alec didn’t. He was shaking his head, his brows furrowed, his eyes searching Magnus’s face, his hands shaking, all but bruising Magnus’s wrists.

                “Alexander, my beautiful Alexander, listen to me—”

                “You want me to go,” Alec said. “You hate me.”

                Magnus’s face fell. “Alec—”

                “It’s all my fault you lost your magic, it’s because of me.”

                “Stop it!”

                “Y-You don’t even want me around, it’s my fault—”

                “No, it’s not—”

                “I’m sorry, I didn’t want you to lose your magic, I-I didn’t—I didn’t know—”

                “Alexander, _enough_!” Magnus said, forcefully pulling his hands out of Alec’s, and he was surprised at the anger in his voice. “I will not humor these ridiculous fears.”

                He knew he might’ve been harsh, but what was Alec saying? How could he insinuate Magnus didn’t love him? That he didn’t suffer at being apart from him? Couldn’t he understand that Magnus had a good reason for what he’d asked?

                “After all I’ve done,” he said, his voice dangerously quiet. “How _dare_ you?” He looked away, his eyes stinging. All this time, and he still hadn’t earned Alec’s trust in him.

                Alec looked stricken. He stepped back, but Magnus’ thoughts were back on Asmodeus. He had to protect Alec. He had to keep him safe. He _had_ to.

                “Leave, Alec,” Magnus said. “Now.”

                Alec said nothing as he took another step back, then another, his eyes on Magnus. His eyes filled with too many emotions for Magnus to decipher at once; grief, sorrow, guilt, anger, loss—and he turned, hurrying out.

                When he was gone, Magnus all but fell into his chair. His tired eyes caught the box of mementos once again, and he looked back to the door from which Alec had left, distraught. Magnus wished he felt anything but pain in that moment, any tiny trace of a spark, a sting… but Magnus felt nothing.

                _“Magnus, if you do this… you_ will _lose everything.”_

                Magnus had not yet lost _everything_ , he knew that, but still… he had a good feeling that Asmodeus was just getting started.

**Author's Note:**

> Okay, I wrote this whole explanation earlier, but the system glitched, and it all vanished, so here are the footnotes:  
> -currently reading cc's books before TRSoM in April (so excited!!(๑˃̶͈̀o˂̶͈́๑))  
> -haven't written anything much as a consequence  
> -always imagined magnus banishing asmodeus  
> -might write real fluff for valentine's day


End file.
